What is an accounting reference date?

How is the accounting reference date set?

A new company's first accounting reference date is the last day of the month in which the first anniversary of its incorporation falls (Companies Act 2006, section 391). Later ARDs fall on the same date every year. Nothing has to be filed to set it; Companies House calculates it automatically.

The ARD is the reference point. Under section 390 the directors may end a financial year on any date up to seven days before or after it, which suits companies that close on, say, the last Friday of a month.

How do you change it?

Companies change the ARD by filing form AA01 online, through software or on paper, before the filing deadline for the accounts of the period being changed has passed. The rules differ for shortening and extending:

From 1 April 2028 a company will need to give a business reason if it wants to shorten its accounting reference period more than once in five years.

Where do you see it in real data?

The Companies House company page shows "Next accounts made up to" and "due by"; the first date is the end of the current accounting reference period. The free monthly register file holds the ARD as two columns, Accounts.AccountRefDay and Accounts.AccountRefMonth, and the public API returns accounting_reference_date with a day and month. In the accounts themselves, and in iXBRL contexts, the period end date is the balance sheet date, which normally matches the ARD or is within seven days of it.

Worked example

Example (illustrative, not a real company): a private company is incorporated on 15 June 2025.

1. First ARD: 30 June 2026, the last day of the month of the first anniversary.
2. The first period runs from 15 June 2025 to 30 June 2026, just over 12 months.
3. First accounts deadline: 21 months after incorporation (15 March 2027), or 3 months after the ARD if later. Here 15 March 2027 applies.
4. If the directors instead file AA01 in February 2026 to shorten the first period to end on 31 March 2026, the period is under 12 months and the normal rule applies: accounts are due 9 months later, by 31 December 2026, or 3 months after the AA01 was filed if that is later.

Shortening a period brings the deadline forward, so the filing has to be planned before the date is changed.

Why it matters when checking a company

The ARD tells you how old the latest accounts can be and when the next ones are due. A private company with a 31 March ARD that has not filed by early January is overdue, unless these are its first accounts or it has changed its ARD. Frequent changes to the ARD, especially repeated extensions to the 18 month limit, can be a way to delay publishing accounts and are worth noticing.

First deadlines are where companies most often slip: on 1 October 2026, 16,436 active companies were past the deadline for their first accounts (overdue accounts data). You can check any company's next due date or work it out with the accounts deadline calculator.

Common confusions

• The ARD is not the filing deadline. The deadline is normally 9 months later for a private company.
• The ARD is not the tax year. Corporation tax follows the company's accounting period, and HMRC deadlines are separate.
• Changing the ARD does not change the incorporation date or the confirmation statement cycle.

Sources

• Companies Act 2006, section 390, section 391 and section 392
• Companies Act 2006, section 442
• GOV.UK: Preparing and filing Companies House accounts

FAQ

How do I find a company's accounting reference date?

Look at the company's page on Companies House: the "Next accounts made up to" date is the end of the current accounting reference period, and its day and month are the ARD. The free register file and the Companies House API also hold the ARD as a day and month. Past balance sheet dates in the filing history show the same pattern.

How many times can you change your accounting reference date?

You can shorten an accounting reference period as often as you like at present, but from 1 April 2028 shortening more than once in five years will need a business reason. Extending is limited to once in five years, with exceptions for companies in administration, Secretary of State approval or alignment with a UK parent or subsidiary, and no period may exceed 18 months.

Can you change the accounting reference date after the deadline?

No. The change must be filed before the filing deadline for the accounts of the period you want to change has passed. Once accounts for a period are overdue, that period can no longer be shortened or extended, so the company must file the overdue accounts on the existing basis and change a later period instead.

Sources: Companies House register and accounts data (Open Government Licence v3.0), legislation.gov.uk and GOV.UK guidance where linked. This page is general information, not legal, tax or credit advice. Spotted an error? Email info@globalmindsetmarketing.co.uk.